The present disclosure relates to the electrical, electronic, and computer arts, and, more particularly, to the handling of small die and electronic components used to fabricate electronic devices.
With shrinking dimensions of various integrated circuit components, transistors such as FETs have experienced dramatic improvements in both performance and power consumption. These improvements may be largely attributed to the reduction in dimensions of components used therein, which in general translate into reduced capacitance, resistance, and increased through-put current from the transistors. Miniaturization has provided benefits to mobile devices such as smart phones, implantable devices, IoT (internet of things) devices, as well as other applications. As the size of circuit components and electronic devices decreases, challenges arise in the assembly of such components.
Temporary wafer bonding/debonding is an important technology for implementing the fabrication of semiconductor devices, photovoltaic devices, and electrical devices of micron and nanoscale. Bonding may include attaching a device wafer, which is to become a layer in a final electronic device structure, to a substrate or handling wafer so that it can be processed, for example, with wiring, pads, and/or joining metallurgy. Debonding may involve removing the processed device wafer from the substrate or handling wafer so that the processed device wafer may be employed within an electronic device.
Various ways of transporting and assembling electronic components have been developed. In the fabrication of semiconductor chips, semiconductor wafers are divided into individual dies. In forming integrated circuits, identical dies are typically fabricated in a repeated pattern on a surface of a semiconductor wafer. Each die includes electronic structures and/or circuits. The individual dies are cut or diced from the wafer, then packaged as an integrated circuit. Wafer dicing involves sawing a wafer comprising electronic components such as MOSFETs or memory devices into individual dies. Before dicing, some wafers may go through a thinning steps such as with back grinding process to thin them down from 780 μm thickness (for 300 mm diameter wafers) or from 730 μm thickness (for 200 mm diameter wafers) to, for example, about 50 μm to 150 μm for very thinned wafers or with wafer thickness up to 600 μm thickness or no thinning for full thickness wafers which is common at 780 μm or 730 μm thickness. Tape is applied to the wafer. Sticky tape allows for safe removal of each die during a subsequent push-up step in the pick-and-place operation. A blade or laser is used to cut the wafer into individual dies without cutting through the tape. The individual dies accordingly remain attached to the tape after the dicing process. Various types of wafer tapes have been utilized in semiconductor processing, such as for dicing processes. UV curable tapes are among those that have been employed. Known good dies (KGDs) are dies that have been electronically tested before being placed in a carrier. A typical KGD is a result of a tested wafer that has been diced.
A pick and place tool may be used to separate the individual dies from the wafer tape. Pick and place tools operate by lifting an individual die from the wafer tape and placing the die onto a package, substrate, wafer or other dies. Eject pin(s) push up through the tape to dislodge a die therefrom. A vacuum collet then lifts the die from the tape and places it into a final package. Positioning (XY) and centering is performed automatically or semi-automatically. Carriers other than tapes have also been developed for storing and transporting singulated devices. After pick and place, (1) the die with area array solder bumps typically go through a solder reflow furnace to electrically connect the die to the package, or (2) the pick and place tool or subsequent multi-die holder (such as a gel pack) may use a thermal compression bonding head for pick and place from a die holder and then apply heat and pressure for bonding, or (3) a wire-bond attach die may be positioned with adhesive and then electrically joined with metal wires between one or more wirebond pads on the die to wirebond pads on a package or other die.